1. Field of the Invention
The present invention relates to a color separation optical assembly and an image capture device.
2. Description of the Related Art
In an image capture device, such as a television camera or a video camera, a color separation optical assembly which separates incident light into three color light components of blue light, green light, and red light is used, and each separated color light component is received by an image capture element, such as a charge coupled device (CCD) image sensor provided for each color light component.
As this kind of color separation optical assembly, a Phillips type color separation optical assembly is known. The Phillips type color separation optical assembly includes, for example, a first prism in which a dichroic film reflecting blue light and transmitting green light and red light is formed on a reflection/transmission surface, a second prism in which a dichroic film reflecting red light and transmitting green light is formed on a reflection/transmission surface, and a third prism, and is configured to extract blue light with the first prism, to extract red light with the second prism, and to extract green light with the third prism.
From the standpoint of increasing sensitivity of the image capture device, for the dichroic film of the color separation optical assembly, typically, a dichroic film which has spectral transmittance characteristics with a comparatively steep slope is used. On the other hand, from the standpoint of approximating the sensitivity of the image capture device to the spectral sensitivity characteristics of the human eye to increase color reproducibility, a color separation optical assembly which uses a dichroic film having broad spectral transmittance characteristics with a comparatively gentle slope is known (for example, see JP2009-75543A).
The image capture element has sensitivity to infrared light which cannot be sensed with the human eye; thus, in order to block infrared light and to obtain characteristics similar to the spectral sensitivity characteristics of the human eye, in the color separation optical assembly described in JP-A-2009-75543, an absorption type visual sensitivity correction filter which cuts infrared light is provided on the light incidence side of the color separation optical assembly. Furthermore, in a color separation optical assembly described in JP-A-2010-26312, a reflection type infrared cut filter which is constituted of a dichroic film is provided on the light incidence side of the color separation optical assembly.